Syrian rebels have seized a border crossing with Turkey as a senior defector warns that the government in Damascus has considered using chemical weapons.

The rebels seized the Tall al Abyad border crossing, north-east of Aleppo, after two days of fighting.

A Turkish woman and her daughter were reportedly wounded by stray bullets during the battle.

Rebels now control at least three of the seven crossings between Syria and Turkey.

The victory could open up a new supply line into northern Syria, but people in the region have been supportive of the government in Damascus.

Meanwhile, The Times newspaper reported the former head of Syria's chemical weapons division, who defected three months ago, says the government discussed using chemical weapons if it lost control of key areas, like Aleppo.

Major-General Adnan Sillu said he defected from the Syrian army after being party to top-level talks about the use of chemical weapons on both rebel fighters and civilians.

"We discussed this as a last resort - such as if the regime lost control of an important area such as Aleppo," he said.

Speaking from Turkey, General Sillu told The Times he was convinced president Bashar al-Assad's regime would eventually use chemical weapons against civilians, adding that the discussion had been "the last straw" which triggered his defection.

He said the government also considered arming the Lebanese Shiite militia Hezbollah with chemical warheads for use against Israel.

His comments come after German press reported this week that the Syrian army had tested a chemical weapons delivery system.

Arms from Iran

Meanwhile, a Western intelligence report says Iran has been using civilian aircraft to fly military personnel and large quantities of weapons across Iraqi airspace to Syria to aid Mr Assad in his attempts to crush the 18-month uprising.

Earlier this month, US officials said they were questioning Iraq about Iranian flights in Iraqi airspace suspected of ferrying arms to Mr Assad, a staunch Iranian ally.

On Wednesday, US Senator John Kerry threatened to review US aid to Baghdad if it does not halt such overflights.

Iraq says it does not allow the passage of any weapons through its airspace.

But an intelligence report obtained by Reuters says Iranian weapons have been flowing into Syria via Iraq in large quantities. Such transfers, the report says, are organised by the Islamic Revolutionary Guard Corps.

"This is part of a revised Iranian modus operandi that US officials have only recently addressed publicly, following previous statements to the contrary," said the report, a copy of which was provided to Reuters by a UN diplomatic source.

"It also flies in the face of declarations by Iraqi officials," it said.

"Planes are flying from Iran to Syria via Iraq on an almost daily basis, carrying IRGC (Iranian Revolutionary Guard Corps) personnel and tens of tons of weapons to arm the Syrian security forces and militias fighting against the rebels."

Although the specific charges about Iraq allowing Iran to transfer arms to Damascus are not new, the intelligence report alleges the extent of such shipments is far greater than has been publicly acknowledged, and much more systematic, thanks to an agreement between senior Iraqi and Iranian officials.

Iraqi officials in Baghdad and New York did not have any immediate comment.